Die holding apparatus



D. V. STROCK DIE HOLDING APPARATUS 2 Shee ts-Sheet 1 Filed y 16. 1941 Whum INVENT OR. DONALD V S 1'12 ocx.

A 7702M? v5.

Aug. 25, 1942. 0'. v. STROCK 2,294,138

DIE HOLDING APPARATUS Filed July 16, 1941 2 Sheets-Sheet 2 FIG 74 I INVENTOR. D QNALDV 512.00

BY *M Patented Aug. 25, 1942 DIE HOLDING APPARATUS Donald V. Strock, Youngstown, Ohio, assignor to.

The Aetua-Standard Engineering Company, Youngstown, Ohio, a corporation of Ohio Application July 16, 1941, Serial No. 402,646 7 Claims. (01. 20545) This invention relates to apparatus for drawing metal tubes and more particularly to improved means for supporting the die of a draw bench or the like.

In the manufacture of seamless tubing the usual procedure is to pierce a billet to form a rough elongated tube. This rough tube is then drawn through a die on a draw bench, it being understood that several drawing operations may be necessary to produce a finished tube of the desired diameter and wall thickness. A mandrel is positioned within the tube while it is being drawn through the die when it is desired to work the inside of the tube as well as the outside and difliculty has been experienced in the drawing operations on the rough tubes due to the fact that such tubes frequently have rough and torn trailing ends which, as they pass through the die and over the mandrel, may scratch the mandrel or die or deposit metal or scale particles thereon. Such scratches and particles, unless they are removed, result in markings on the subsequently drawn tubes and it is among the objects of my invention to provide a die supporting mechanism whereby the danger of injury to the surfaces of the die and mandrel is greatly reduced.

Other objects of my invention are: the provisions of a die support whereby the space or gap between a die and mandrel may be increased at the will of the operator; the provision of a die support which will maintain the die firmly in proper position during the drawing operation but which may be substantially instantaneously retracted from its drawing position and then returned to drawing position; the provision of a die support for drawing rough tubular products whereby scratching or depositing of metal on the die or mandrel is prevented; and the provision of an extremely rugged, simple, and effective releasable support for the drawing die of a draw bench or the like.

The above and other objects of my invention will appear from the following description of one embodiment thereof, reference being made to the accompanying drawings in which- Fig. l is a diagrammatic side elevation of a draw bench embodying my improved die support;

Fig. 2 is a fragmentary end elevation, looking in the direction of tube movement, and showing a portion of a die stand with my improved die support installed therein;

Fig. 3 is an enlarged vertical cross-section view the reduced end 3 of the tube.

taken substantially on line 3-3 of Fig. 2 and showing the die in tube drawing position;

Fig. 4 is a view similar to Fig. 3 but illustrating the die in retracted position, the tube end bein about to pass through the die;

Fig. 5 is a diagrammatic layout of the fluid piping and connections for operating my releasable drawing die.

In Fig. l the draw bench is illustrated at I and supports a traveling carriage 2 which grips the tube 3 and is moved over the bench by a driven chain 4. The hook 5 on the carriage 2 engages the chain in well-known manner and suitable gripping jaws are provided for grasping The stationary die stand or support 6 is located ahead of the bench land the mandrel bar I carries a man- 'drel 8 and is supported at its outer end in any suitable and Well-known manner.

As is best seen in Figs. 3 and 4, the die stand 6 is recessed to accommodate the die holder 9 which has a sliding fit in the bore ll] of the stand 6. A removable die I i is mounted in the die holder 9 and it will be understood that different dies and mandrels will be employed to draw difierent sizes of tube. Stop bars l2 and i3 extend across the top and bottom of the bore in the die stand 6 and are secured by screws l4 and 15. The flange portion [6 of the die holder 9 is formed with an annular convex curved surface I! and a corresponding convex curved sur-- face I8 is formed in the die stand 6. In the space or chamber defined by these curved sur faces and the walls of the die stand and die holder a flexible heavy walled tube l 9 is disposed. This hollow member [9 is preferably of rubber, or a synthetic rubber composition, and is provided with an inlet pipe 20 which extends through Although the die II and pot or die holder 9, as illustrated, are separate parts in order to facilitate changing dies, it will be understood that the die itself might be engaged directly by a hollow member IS in which case the holder 9 and die I I would become a single part. Thus, where the term die is used in the appended claims it is intended to include either a one-piece die member engaged directly by the resilient tube or a die holder and die assembly as particularly illustrated and described herein.

The connections to the tube 19 are illustrated in Fig. 5 and include a pipe 22 which extends from the inlet pipe 20 to a tank or vessel 23.

the die stand and is clamped in position by a nut A quick acting shutoff valve 24 is installed in the pipe or conduit 22 between tube [9 and tank 23 and air or other gas under pressure is applied to the top of the tank 23 from any suitable source of supply (not shown) through the pipe 25.

When my apparatus is in operation the tube l9 and pipe 22 are first completely filled with a substantially non-compressible fluid such as oil, water, Prestone or the like and the fluid level in the tank 23 is maintained at a point somewhat below the top of the tank. Air, preferably under substantially constant pressure, is applied to the surface of the fluid in tank 23 at all times and it will be seen that, when the valve 24 is open, the pressure exerted by the air in the tank 23 will tend to force liquid into the hollow flexible member l8 and distort same from its normally circular cross-section into the oval shape shown in Fig. 3. When this occurs the die holder 9 will be moved to the left until it abuts against the stop bars l2 and i3. In this position the mandrel 8 and the die II are so located that the proper drawing clearance is provided therebetween.

In the operation of a draw bench equipped with my improved die holder 9. tube having its end crimped in the usual manner is pushed through the die, the mandrel being in position in the tube. The valve 24, which is open, permits air under pressure from pipe 25 to force the substantially non-compressible liquid into the tube l9 and move the die holder 9 and die I I as a unit into drawing position as determined by the stop bars I2 and I3. With the die in this position the operator closes the valve 24 thus trapping the non-compressible fluid in a completely filled closed system. As the hollow member l9 cannot yield the die holder and die are held firmly in drawing position while the tube end is grasped by the jaws on the carriage 2 which draws the tube through the die over the mandrel. The operator observes the movement of the tube through the die and just before the rough trailing end of the tube is about to enter the die he opens the quick acting valve 24 (which can be located in any convenient place) which immediately releases the liquid trapped in the tube I9 and pipe 22 and the pull on the die I I from the tube 3 as it is moved by the carriage 2 will compress the tube !9, forcing a part of the liquid therein back through the pipe 22 and valve 24 into the tank 23 against the constant air pressure maintained in the tank through the pipe 25. The air pressure on the tank 23 is not sufiicient to interfere with this backing up of the liquid as such air pressure need only be enough to expand the tube l9 and move the parts into drawing position.

A stop flange 28 is formed on the die stand 6 and engages a corresponding flange 21 on the die holder 9 to limit the movement of the die holder and die in the direction of movement of an article being drawn. The travel of the die in releasing direction is such that the clearance between the die and the mandrel 8 will be increased sufficiently to permit the rough trailing end 3" of the tube 3 to be drawn over the end of the mandrel and through the die without scratching or depositing scale or metal particles.

After the end of the tube has passed through the die the air pressure causes liquid to rc-enter the flexible tube [9 and move the die back to drawing position as seen in Fig.3. As soon as the die is thus returned to drawing position, which is an almost instantaneous operation, the operator closes the valve 2!, locking the non-compressible liquid in the tube l9 and forming a non-resilient support for the die preparatory to drawing another tube. As the resilient tube I! is completely surrounded by rigid enclosing walls, and as the liquid contained therein is substantially non-compressible, the die holder and die will remain in drawing position until the operator again opens the valve 24.

It will be understood that the relative position of the mandrel and die can be changed in the usual manner, by a mandrel rod adjustment, to suit the wall thickness of the tube being drawn. With my quick-releasing die, the operator can efiectively prevent damage to the die or mandrel and although I have illustrated and described in considerable detail one embodiment of my invention, it will appear to those skilled in the art that numerous variations and modifications, both in the structural form and the arrangement of the parts, may be made without departing from the spirit of my invention. I do not, therefore, wish to be limited to the exact form of the apparatus herein disclosed but claim as my invention all embodiments thereof coming within the scope of the appended claims.

I claim:

1. In apparatus of the type described, a stationary die support, a die mounted for movement in said support, a flexible tubular member of resilient rubber or the like material interposed between and engaging said die support and die, means for limiting the movement of said die relative to said support, a fluid conducting conduit connected to said flexible tubular member, a valve in said conduit, and means for supplying a substantially non-compressible liquid under pressure to said conduit and tubular member.

2. In apparatus of the type described, a stationary die stand, a die slidably mounted in said die stand for movement along the line of travel of an article being drawn, means for limiting the movement of said die in said die stand, a flexible tubular member substantially completely enclosed between said die stand and die, a fluid conducting conduit connected to said flexible tubular member, means for supplying a substantially noncompressible fluid under pressure to said conduit and tubular member, and a shutofl valve in said fluid supply means.

3. In apparatus of the type described, a die stand, a die supported in said stand for movement along the line of travel of an article being drawn, said die stand and die being shaped to form an enclosed chamber therebetween, a flexible hollow member disposed in said chamber and adapted to exert pressure tending to move said die along said line of travel, conduit means for supplying a substantially non-compressible fluid to said hollow member, and shutoff valve means in said conduit.

4. In apparatus of the type described, a die stand, a die supported in said stand for movement along the line of travel of an article being drawn, said die stand and die being shaped to form an enclosed chamber therebetween, a flexible hollow member disposed in said chamber and adapted to exert pressure tending to move said die along said line of travel, conduit means for supplying a substantially non-compressible fluid to said hollow member, shutoff valve means in said conduit, and means for limiting the movement of said die along said line of travel of an article being drawn.

5. Die supporting apparatus including a stationar'y support, a die mounted in said support for limited movement along the line of travel of an article being drawn through the die, a flexible hollow member interposed between said die and support, a fluid conducting conduit leading into said hollow member, means for supplying fluid under pressure to said hollow member through said conduit and shutofi valve means in said conduit. v

6. Die supporting apparatus including a statioriary support, a die mounted in said support for limited movement along the line of travel of an article being drawn through the die, a flexible hollow member interposed between and engaging said die and support, a fluid conducting conduit leading into said hollow member, shutoff valve means in said conduit, a reservoir for liquid connected to said conduit, said hollow member and conduit being filled with a substantially noncompressible liquid and said reservoir being partially fllled with said liquid, and means for'supplying fluid under pressure to said reservoir on top of said liquid.

7. Die supporting apparatus including a stationary support, a die mounted for movementin said support along the line of travel of an article being drawn through said die, a flexible hollow member interposed between said die and support and adapted to exert pressure tending to move said die along said line of travel, stop means for limiting the movement of said die in a direction opposite to the direction of movement of an article being drawn, independent stop means for limiting the movement of said die in the direction of movement of an article being drawn, a source of supply of liquid under pressure, conduit means connecting said source of supply and said hollow member, and means for controlling the flow of fluid to and from said hollow member.

- DONALD V. STROCK. 

